A known oil pressure control apparatus is disclosed in JP2009-299573A (hereinafter referred to as Patent reference 1). The oil pressure control apparatus disclosed in Patent reference 1 includes a control apparatus (i.e., a valve timing control apparatus) and an engine lubrication apparatus. The control apparatus includes a pump (i.e., an oil pump) driven by a rotation of an engine to discharge the oil, a driving side rotation member (i.e., outer rotor) rotating synchronous to a crankshaft, and a driven side rotation member (i.e., inner rotor) arranged coaxially with the driving side rotation member to synchronously rotate with a camshaft, and controls a timing for opening/closing a valve by changing a relative rotational phase of the driven side rotation member relative to the driving side rotation member by supplying and discharging the oil. The engine lubrication apparatus is configured to lubricate each portion of the engine by the application of the oil supplied by means of the pump.
The oil pressure control apparatus disclosed in Patent reference 1 includes a priority valve which restricts a flow amount of the oil from the pump to the engine lubrication apparatus and prioritizes the supply of the oil from the pump to the valve timing control apparatus when a hydraulic pressure applied to the control apparatus is lower. Thus, when the rotation speed of the pump is lower, the hydraulic pressure applied to the valve timing control apparatus is ensured on a priority basis, and the valve timing control apparatus is appropriately operated without an electric pump which assists the operation of the pump.
In those circumstances, notwithstanding, the oil pressure control apparatus disclosed in Patent reference 1 controls the priority valve with an oil switching valve (i.e., opening/closing valve) which is configured to operate in response to a driving state of the engine to selectively supply the oil to a pressure increasing mechanism. Accordingly, in a case where the oil pressure control apparatus disclosed in Patent reference 1 is actually mounted to the vehicle, a manufacturing cost may increase.
A need thus exists for an oil pressure control apparatus which is not susceptible to the drawback mentioned above.